wild bees and native bees

Why do I see mining bees in September?

Mining bees in September: Many ground-dwelling bees are active in fall. This tiny Lasioglossum female, commonly known as a sweat bee, is foraging on an Alyssum flower. © Rusty Burlew.

Many ground-dwelling bees are active in fall. This tiny Lasioglossum female, commonly known as a sweat bee, is foraging on an Alyssum flower.

Questions about mining bees in September

In the past week, I received two nearly identical questions about mining bees. Both writers wanted to know why they had mining bees in September while everyone says that mining bees appear in the spring. Excellent questions.

DJ wrote:

All I read about these bees indicates they are usually around in early spring, but mine are here now and intermittently throughout the summer. Is that normal? I have a lot of flowering plants like catmint which all of my bee friends seem to love and I’m wondering if they are just visiting me longer because of all the pollen and goodies. I feel bad they have landed where they did because it is near where we walk for our hose and I am always walking on their little mounds of sand and soil.

Shortly afterward, Keith wrote:

I was never aware of mining bees until this past week when literally thousands of them were hovering over a bare area on the property. My question is most comments seem to refer to spring, and a relatively short span of activity. But this is early September! Does timing of activity vary that much with species, or is something else going on? I hadn’t seen the myriad of individual, small holes in the ground until I got down on my knees to look at/try to identify the fliers. From a standing position, it was impossible to see what they were because of their small size and rapid movement.

I love that these two people have enough confidence in their observations to question what they’ve heard about mining bees in September. And of course, they are both right. The species that are active change throughout the year, but some species will be around as long as flowers are blooming.

Are they native, wild, or feral?

Any discussion about bees has to begin with the words we use to describe them. There doesn’t seem to be a standard, but you can categorize bees by how they got here.

For example, most of the bees here in North America are native to the continent and were here when the colonists arrived. But others have been introduced on purpose and subsequently escaped into the environment. These escapees became established, much like introduced weeds. Examples are wild populations of the European honey bee and the alfalfa leafcutting bee.

Still, other bees were introduced accidentally and were never managed, such as the European wool carder bee. All three of these categories can be referred to as “wild.” The opposite of wild bees includes those that are currently managed, such as most European honey bees.

Common bee names are confusing

When it comes to identifying bees, I again think it’s the names that confuse people. For example, many people use the term “mason” bee to refer to bees in the genus Osmia, but in a larger sense, mason bees are any bees that collect building materials from their environment. So that makes leafcutting bees, wool carder bees, and pebble bees masons as well.

Likewise, the terms “mining bee,” “digger bee,” and “sweat bee” each comprise hundreds and sometimes thousands of different species. So when one person describes what he considers a mining bee, it probably isn’t the same species that someone else is calling a mining bee. These names are based on broad descriptions of behavior; they are not names of specific species.

Sometimes there is a bit of correlation that develops over time. For example, the term “mining bee” is often used to describe bees in the genus Andrena, while “digger bee” is used for the genus Anthophora, but both are large groups of bees that dig small holes in the ground. The genus Andrena alone comprises 1300 species.

What people need to realize is that Earth is home to roughly 20,000 named species of bee and probably another 10,000 to 20,000 unnamed ones. So when you use a label like “digger bee” you have to understand that the word encompasses a wide range of bees and bee behavior.

Mining bees appear in different seasons

Going back to the original questions, both DJ and Keith mention hearing that mining bees appear in the spring, but their mining bees are busy in September and intermittently during summer. All I can say is they are quite observant.

In truth, different species of bees become active at different times of the year. A species can become active in late winter, early spring, mid-spring, late spring, early summer, mid-summer, late summer, early fall, and so on. Each species is different and each one has a specific time when it becomes active. Its active time usually correlates with the flowering plants it prefers. When those flowers bloom, the bees “bloom” as well.

Unlike honey bees which do not hibernate, most bees spend the majority of their lives in the nest either as a larva or a pupa. The time spent in the nest varies with species, but as a rule of thumb, you can imagine bees spending about 10 months in the nest and two months as active adults.

When we say bees “become active” we mean the adults emerge, mate, lay eggs, and gather provisions for their young. Once this work is done, the adults die and the next generation is on hold for 10 months until next year.

Species come and go throughout the year

So when DJ says her bees are active intermittently, what she is seeing is different species coming into their active period at different times of the year. Of course, nature is complex and nothing is easy to pigeonhole.

For example, there are species of bees that have two life cycles in one year. Other bees—like some of the bumbles—appear to have longer active periods because they live in colonies that persist for months. And the real outliers, colonies of honey bees, do not have a dormant or hibernating stage at all. But for most species, the life cycle is less than 2 months of activity followed by 10 months holed up in the nest in an immature form.

Without actual specimens, it’s impossible to say if the mining bees DJ saw in September are the same species she saw in spring. Maybe yes, maybe no. But in any case, they would not likely be the same individuals.

Because bees become active along with the flowers they prefer, the mix of bees changes with the mix of flowers. That means if you were to inventory all the bees in your backyard on May 1 you would have a very different list than you would on a different date, let’s say August 1. Honey bees would be on both lists, and maybe some of the bumble bees, but the others would be different. Even if you were to compare inventories one month apart, say May 1 and June 1, you would see a big difference. Just as the flowers change, so do the bees.

Spring brings lots of variety

I agree that people say mining bees are active in the spring and then disappear, and I’m sure I’ve said that too. The reason, I think, is that many more species are active in the spring than in the fall, just as many more flowers bloom in the spring. But that doesn’t mean there are no mining bees the rest of the year. Bees are all over the place, and many of them find flowers the rest of us barely notice.

The same applies to mason bees. When people say masons are only active in the spring, they are talking about specific species, maybe Osmia lignaria or Osmia aglaia. But there are also very early masons, late spring masons, summer masons, and so on.

DJ mentions the number of flowering plants she has and wonders if that is a cause for all the bees. Absolutely! Remember bees and flowers are dependent on each other, and where you find a lot of one, you will find a lot of the other. The more flowering plants you have, the more bees you will have, and not just in numbers but also in variety. That is why flowers are so important to bee conservation: more varieties can support more species of bees.

Walking on bee mounds

DJ’s last question is about walking on the mounds, technically known as tumuli. If you go out of your way to destroy all the tumuli all of the time, you will do damage to your bee population. On the other hand, If you accidentally step on a few now and then, the bees will quickly repair the damage. Like many things in nature, it’s a matter of degree.

I recommend you use your yard normally and not worry about the mounds. I’ve seen soil-nesting bees in playgrounds, ballparks, picnic areas, backyards, and parking lots. They survive just fine as long as we don’t go out of our way to destroy them.

The holes come in many sizes

Keith mentions the holes in his yard are very tiny, while others claim they are quite large. But once again, the size of the hole is species-dependent. Of the 20,000+ species of bee in the world, fully 70% live in holes in the ground. That means there is an enormous variation in size, density, depth, seasonality, and soil types involved. The world of bees is anything but simple.

I don’t know if I clarified anything or not, but I love hearing from people who care. Most people ask how to kill mining bees, even in September, so it’s a pleasure to hear from the others.

Honey Bee Suite

About Me

I backed my love of bee science with a bachelor’s degree in Agronomic Crops and a master’s in Environmental Studies. I write extensively about bees, including a current column in American Bee Journal and past columns in Two Million Blossoms and Bee Craft. I’ve endured multiple courses in melittology and made extensive identifications of North American bees for iNaturalist and other organizations. My master beekeeper certificate issued from U Montana. I’m also an English nerd. More here.



  • Thank you for this very clear and detailed answer to our questions. It has explained quite a bit. I have been careful not to trample the mounds as much as I can. They are everywhere, so it is sort of like playing “the floor is lava” but I find it amusing. I have been watching these little workers more closely since they arrived and the yellow pollen filled visitors are quite mesmerizing. Happy to have them around as long as they are here and hope to see them every year!

    Thank you again. Great article.

  • We seem to have a bumper crop of yellowjackets attacking our honey bee hives this year. I learned from another beekeeper a non-chemical way to address this problem. Get some tuna-flavored cat food and put a couple of spoons full in a flat dish with a few drops of dish detergent and about an inch of water. Set it near the hives. The yellowjackets will be attracted to it and drown but the honey bees will not go to it.

  • By the way, do any of these ground dwelling bees (other than bumbles) have a stinger?
    I have assured worried mothers that their children are safe but I have nagging doubts too.

    • Mike,

      With very few exceptions, all female bees can sting. Most use their stinger for self-defense from predators. That said, most native species are not aggressive and most are so small their stingers can’t penetrate human skin. However, there are those that can pack a wallop if you were to endanger them. The males, of course, cannot sting.

  • Thank you Rusty –

    As I become somewhat better at recognizing all these different bees, my awe for their diversity only increases. The more I seem to recognize them the less I feel I know about them.

    Thanks, GB

  • Wow! You did a great job, covering so much ground and explaining the intricacies of common names and varieties of bees.

    Here is a list of non-native bees for those who are interested:

    I envy those who have abundant bee nests in their properties.

    Mike, I read about a school that discovered such aggregation of bee nests in their school yard and adopted the bees with great enthusiasm. I haven’t heard about any unhappy events. I wish I could find the link.

    I discovered one aggregation next to a parking lot of a busy park. This was seven years ago and last I heard, they are going strong, more than forty nests, this year. https://www.facebook.com/beatriz.moisset/videos/4417380311997/

      • Every September the bees take over my front garden and I leave them to it. I cancel the window cleaner so they will not be disturbed; it’s lovely to see them.

  • I started 2 hives 1 month ago. One hive is doing well with a lot of activity and reproduction while the other is basically at a stand still. They are side by side yet the difference is notable.The queen in the lackluster hive seems to be ok and active yet no growth and very docile while the other hive is very aggressive and has started producing cells in a new frame. Any idea why and is there anything that can be done?

    Thank you for any help you can provide. Thank you, Alex

  • The miner bees are in the ‘flower’ garden. Many many, many of them, and I feel guilty when I weed. All those homes I am destroying!! However, my garden is failing rather badly, embarrassingly so this year, (as in dead!) and I am wondering if the bees are playing any part in that. Root destruction? I certainly do not wish to do them harm, but I would like to dig out the bed and refurbish it with richer soil (that won’t be hard!!), and new plants. As I seem to have miner bees all year round it is not as if I can wait 12 weeks and they will be gone … Any suggestions gratefully received.

    Kay (Baxter)

    • Kay,

      Tunneling bees do not hurt your plants, in fact the tunnels aerate the soil, which is a good thing. Bees are totally uninterested in roots, but they are part of a healthy ecosystem. Something else is bothering your garden. If you dig out the garden, you will kill the bees you dig out. There’s not anything you can do for them because moving them generally doesn’t work.

      • We have a small area, with several flagstones. Some years ago, we began getting cicada killing wasps nesting in that area. For the past few years, we’ve had what appears to be digger bees in the same area in late summer. Is there any way to deter them from this area without killing them? I’m allergic to stinging insects, but recognize them aa non-aggressive, but would be more comfortable if they weren’t in this area where I need to go through to get to my water faucet. Thank you

  • Our mining bees have now gone into hibernation but I’ve noticed that something appears to be attempting to dig up the holes. Do mining bees have any predators? I’m guessing perhaps hedgehogs are interested in the larvae underground.

    • Lorraine,

      Lots of animals eat grubs and larvae, so I’m sure there are some that love immature bees. I don’t know which ones they are, however.

  • We recently (last week) unintentionally disturbed a nest of ground bees that had clearly been very happy. They came to defend the nest, so we dropped a rock over the opening that we made. That seems to have calmed things down a bit, but now they are easily agitated by the lawnmower. How can we either get them to move or settle them down for the winter without destroying them? Should I put more dirt next to the entrance? I have been watching the hole and they are not aggressive unless one removes the rock (yes, I got stung—it was a very sharp sting, but seemed more like a mosquito bite after) or lawnmower. They appear to be small, not furry bees. We are in western Massachusetts. I have been reading as many websites as I can find, and there is a lot about killing them. Thanks for all this great information to support bees.

    • Kristin,

      It’s hard to say without a photo, but this sounds like a nest of ground-dwelling social wasps. Most ground-dwelling bees, except bumbles, are solitary for the most part.

  • I have mining bees in my lawn that appear in the last 2 hot weeks in September. I now have myriad of holes in my lawn!

    Thank you for the information.

  • We have a huge area of miner bees in our garden. They are very active in September. I am worried as they are in part of the garden that we have to landscape starting in May. These holes are currently in the exposed subsoil and we have to put a layer of topsoil over this and then prepare the area to turf. Is this going to harm my bees? We have been renovating for the past three years so they have been undisturbed so have grown in size. What advice can you give, we are in the UK.

    • Sam,

      I suppose some may survive, but changing the depth of the soil and adding turf (which they hate) will probably drive any survivors away. The depth they choose for nesting varies with the species, so it’s hard to say how many will be able to dig themselves out. Roots from the turf can grow into and obstruct the tunnels, as well. All in all, it’s probably a loss for the bees.

    • I don’t know Sam’s circumstances, but hypothetically could he maybe dig up blocks of the subsoil and move a few to a more out-of-the-way location. Maybe just enough to give a few starter bees a survival chance, with some alternate bare earth spot?

      • Roberta,

        I’ve heard of people trying this will little success, but that doesn’t mean it’s not worth a try. Different species will behave differently, so it’s hard to judge. Some kinds burrow down many feet, others nest near the top.

  • Hello bee people!

    This is a wonderful blog! I am not a beekeeper at all, just a novice home gardener with a bee sting allergy and a small garden.

    I have been watching the bees in the garden with great admiration all summer long. I know how hard they work and I planted a wildflower/butterfly garden and a long row of a variety of sunflowers in the back of the garden for these industrious pollinators (and myself too) to enjoy.

    I also have about ten well-attended bird feeders in the yard.

    Recently over the last month or two, I have run out of room in my home, and put a lot more potted plants outside on the table near the house. I have two small tomato plants, two aloe vera plants, some lavender, basil, and a palm tree out there. Over the last several weeks, I have noticed more and more honeybees or fuzzy bees that look like honeybees anyway, hanging around those potted plants. First, there were only two or three and they were only on the basil and lavender, and only at the bottoms, but now there are about ten or twelve and they seem to be digging in the dirt of the basil plant. They have grown in numbers to the point that they are flying around everywhere I go in the garden now, and are somewhat “aggressively” flying at me and around me. I say aggressively, but maybe I should just say, “With serious intent.” They have not yet stung me, and my dog ate one today because she heard me squeak with a little fear at the last one to come at me. I try not to freak out, but I am not sure how I can spend any time harvesting, pruning, or even filling the bird feeders because these bees keep coming at me.

    Any advice is welcome, even if it’s just to only go out early in the morning or later in the evening with a flashlight…the birds are getting annoyed that I haven’t filled the feeders or changed the water, so I will have to do that soon.

    Thanks, everyone!

    • Michelle,

      It’s hard to give any details, but since they are digging, they are not honey bees. Most digging bees are not aggressive and don’t sting unless threatened. They usually disappear after about a month, so you will just have to decide how much you are willing to put up with.

  • I have had ground bees for a few of years. I feed them along with the birds. This year I am noticing that they are still around and it is September (frost is starting this weekend). I still have some flowers but should I stop putting out fruit and sugar water?

    • Rebecca,

      If you continue to feed sugar water, no harm will come to the bees. They know when it is too cold to fly and are capable of making good bee decisions.

  • I live in the UK and today found an Ashy Mining Bee on the ground. It didn’t try to fly away from me or anything when I got it to climb on my hand. It seems pretty weak so I gave it some sugar water and left it in a box out of the wind…it has been very windy today. This was at a stable yard and it was settled when I left (there is still a teaspoon of sugar water next to it).

    I didn’t know what to do for the best as it is October and there are no flowers out anymore. Will she hibernate when I let her go or will she die?

    • Coral,

      Most likely this bee was at the end of its natural lifespan. The adult forms only survive four to six weeks, and after that, they die. Only the immature forms survive the winter in their burrows. There is nothing you can do.

  • Hello, I live in Nevada, USA. I’ve always been fascinated by bees and I can easily spend a good chunk of time just watching them work. My son and I were outside in an area of my yard that rarely gets foot traffic this morning and discovered some- what I now know to be- miner bees at the base of my house (along a flagstone walkway). They are so cute and I feel honored that they chose my property to settle in on. I didn’t know what type of bees they are, so I had to look up ground-dwelling bees.

    Thank you for your informative website.

  • Thank you for this information it’s very useful.

    I’m in the UK and I too have bees in my lawn in September. They don’t cause any problems and I can mow over them with care.

    I did however have to get up early this morning to plant some bedding plants as I didn’t want to disturb them they woke up as soon as the sun was on them!

    • Linda,

      It sounds lovely. I so love the ground-nesting bees, so friendly and peaceful. They also aerate the soil…good for all those bedding plants.

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